Bore-sighting adapter



Jan.'16, 1945. J. H. KLoPP ETAL BORESIGHTING ADAPTER Filed Dec. 3, 1943 2 Sheets-Sheet 1 FIGURE xx OEN Y R l h@ mc. WHKFMO T J H w/ NJ R v E E v. MKD. m NN mm MN um KLOPP Y EY INVENTOR.

RY F. FINKE JHN ERNEST R. KOSCERA Q MA J. H. KLOPP EI'AL BORESIGHTING ADAPTER Fld 1396.*3. 1943 NN N N BN. NN .WN m

Jan. 16, 1945.

Patented Jan. 16, 1945 UNITED STATES PATENT OFFICE BORE- SIGHTIN G ADAPTER Application December 3, 1943, Serial No. 512,742

6 Claims.

This invention relates to a device to determine the clearance between the path of the bullet and Structure which is to be protected from injury by gun re.

The guns in a gun turret mounted on a vehicle or craft are equipped with interrupters in the fire control circuits which are designed to prevent the gunner from inadvertently shooting off the projecting parts of the vehicle or craft. After the turret and gun re interrupters are installed on the vehicle or craft, it is necessary to check the alignment of the guns with respect to the interrupter mechanism to determine the clearance of the guns around the silhouette of the projecting portions of the craft. For reasons of design, particularly in aircraft, it is necessary in some instances to have the path of the bullet clear the tail surfaces by at least 2 to 4. Due to the compact design of all aircraft power turrets, it is practically impossible to boresight the guns while the gunfire interrupter cams are being checked by any sighting device through the barrels of the guns.

An object of this invention is to provide a sighting device to check the clearance of guns around the structure of the aircraft.

Another object of the invention is to provide a sighting device wherein the actual degrees of clearance may be measured.

A further object of this invention is to provide a sighting device for use with a standard borescope to determine the clearance of the path' of the bullet and the structure of the aircraft.

Further and other objects will become apparent from the description of the accompanying drawings which form a part of this disclosure and in which like numerals refer to like parts.

In the drawings:

Figure 1 is a perspective view showing the tool in use.

Figure 2 shows a plan view, partially in section, of the invention mounted on the muzzle of a gun.

Figure 3 shows a 'section on the line A-A of Figure 2.

Figure 4 shows a section on the line B-B of Figure 2.

Figure 1 of the drawings shows a standard an gle-borescope I attached to the clearance fixture, generally indicated as 2, mounted in the barrel of a machine gun 3. The xture consists of bracket 4, having a stem 5 mounted therein, by portion 6 and secured by set screw l. Portion 5 fits into the barrel of the gun 3 with a snug t. Bracket 4 has a borescope mounting 8 movably mounted thereon, to move along bracket 4 in an arcuate path determined by surfaces 9 whose center of curvature is the pivot point of the gun. A rack I0 is mounted on bracket 4 to cooperate with gear II which is turned by knurled wheel I2 to move portion 8 with respect to bracket 4. An index I3 cooperates with the scale I4 calibrated in degrees, to indicate the angular position of the centerline of the borescope mounting portion with respect to the centerline of the barrel of the gun.

Figure 3 illustrates how the motion and locking of borescope mounting 8 is effected. As pointed out above, gear II mounted on shaft I5 is moved by knurled wheel I2 secured thereto on rack I0, thereby moving the borescope mount along the scale on bracket 4. Knurled wheel I6 acts as a nut on threaded portion Il of shaft I5 to clamp blocks I8 and I9 which are mounted in borescope mount 8, to portion 20 and the edge of the rack I0.

Figure 4 illustrates how portion 8 is held firmly against the arcuate surfaces 9 to cause the borescope mount to move radially to surfaces 9. In cavity 2|, pins 22 are mounted in member 8. Pins 23 are mounted in member 24 which slides along the inner surface of member 20. Compression springs 25, held in place by pins 22 and 23, urge member 8 against arcuate surfaces 9. Since there are two such resilient assemblies on each side of the centerline of member 8, the borescope is held by this member in a position along a radius of arcuate surfaces 9. Cover plates 21 are provided for cavities 2l.

When the borescope is mounted in member 8, knurled wheel I6 may be loosened to permit shaft I5 to be turned by wheel I2 which moves the gear along the rack and thereby the borescope mounted in member 8, to the zero position on the scale. At this point, the borescope is aligned with the axis of the barrel of the gun and by looking in eyepiece 26, the gun may be sighted or aligned. If it is desired to determine the clearance of the gun fire around any objects at relatively close range, it is merely necessary to point the gun and move member 8 along the scale until it is aligned with the object and the clearance can be measured on scale I4.

This is particularly useful in checking gun nre interrupters on the machine guns of gun turrets mounted on aircraft or other vehicles. The gun fire interrupter is a mechanism designed to interrupt the electrical firing circuit of the gun for a predetermined silhouette of the portions of the craft which may come into the line of the fire. The clearance of near by portions is relatively small, While a greater margin of clearance should be allowed for portions of the craft more remote from the gun due to the various factors which effect the path of travel of the projectiles. With this fixture in place, the gun may be traversed over a path, while observing the operation of the interrupter circuit as the gun nears the surface of the craft, the interrupter circuit will operate and the gun may be stopped and the clearance of the gun around the portion of the craft determined from the scale I4.

Another use of this device will be in determining the silhouette of the interlupter mechanism by tracing the silhouette of the projecting portions of the craft by sighting through the borescope and from the gun fire interrupter mechanism, the silhouette may be determined or checked.

It is to be understood that certain changes, a1- terations, modifications and substitutions can be made without departing from the spirit and scope of the appended claims.

We claim:

1. A borescope fixture comprising a bracket member, means for removably mounting said bracket member on the barrel of a pivoted gun, said bracket member having an arcuate surface concentric with the pivot axis of said gun, and means to mount said borescope on said arcuate surface to move relative thereto, to maintain the axis of the borescope radial with respect to the pivot axis of said gun.

2. A borescope fixture comprising two portions, one fixed portion adapted to be removably secured on the barrel of a pivoted gun, said portion having a curved outer surface concentric with the pivot axis of said gun, a second portion adapted to be mounted on said fixed portion and slide on said curved surface so that an axis thereof intersects the pivot axis of the gun, means to mount a borescope on said curved surface radially with respect to said curved surface and means to move said second portion relative to said first portion.

3. A borescope xture comprising two portions, one fixed portion adapted to be removably secured in the barrel of a pivoted gun, said portion having a curved outer surface concentric with the pivot axis of the gun, a scale calibrated in degrees adjacent said curved surface, a second portion adapted to be mounted on said xed portion and slide on said curved surface, means to mount a borescope on said curved surface radially with respect to said curved surface and means to move said second portion relative to said rst portion, an index on said second portion cooperating with said scale whereby the angular displacement of the centerline of the borescope and the centerline of the gun may be determined.

4. A borescope clearance fixture comprising a bracket member removably mounted on a pivoted gun barrel, means to mount a borescope on said bracket member, guide means between said bracket member and borescope mount whereby f an axis of said borescope mount is maintained in intersecting relation with the pivot axis of the gun as the two are relatively moved, and scale means to measure the angular displacement of the axis of said borescope from the axis of said gun barrel.

5. A borescope mount comprising a bracket member adapted to be fixed on the barrel of a pivoted gun, a borescope mounting member mounted on said bracket member guide means between said bracket member and borescope mount whereby an axis of said borescope mount is maintained in intersecting relation with the pivot axis of the gun as the two are relatively moved, means whereby said mounting member may be so moved with respect to said bracket member to selectively align the borescope with the barrel of the gun at a selected angular position relative thereto, and means to lock the borescope relative to the gun barrel in any selected position.

6. A borescope xture comprising a bracket member, means for removably mounting said bracket member on the barrel of a pivoted gun, said bracket member having an arcuate surface concentric with the pivot axis of said gun, means to mount said borescope on said arcuate surface, calibration and pointer means on said bracket and said borescope mount cooperating to indicate the angular displacement of said borescope mount relative to said bracket, and means to move said borescope mount relative to said bracket member.

JOHN H. KLOPP. ERNEST R. KOSCERA. HARRY F. FINKE. 

